Tinker Codehttps://farsthary.wordpress.com
R&DThu, 01 Feb 2018 19:51:15 +0000enhourly1http://wordpress.com/https://s2.wp.com/i/buttonw-com.pngTinker Codehttps://farsthary.wordpress.com
Happy new year!https://farsthary.wordpress.com/2017/12/27/happy-new-year/
https://farsthary.wordpress.com/2017/12/27/happy-new-year/#commentsWed, 27 Dec 2017 08:30:47 +0000http://farsthary.wordpress.com/?p=3210A year is fading, not before bringing us a lot of wonders, a lot of fantasy and art in the hands of countless magicians around the world. Everyday I feel grateful of being part of the amazing people that makes imagination meet reality.

-What do you do? …once in a while a friend ask, and all I can answer is: -where dreams come true!

The great Pixologic team is wishing you all the best for this new year and much more great things awaits for us all.

]]>https://farsthary.wordpress.com/2017/10/06/amazing-zbrush-summit-2017/feed/0farstharyAdobe Industry Certificationshttps://farsthary.wordpress.com/2017/01/24/adobe-industry-certifications/
https://farsthary.wordpress.com/2017/01/24/adobe-industry-certifications/#commentsTue, 24 Jan 2017 23:32:38 +0000http://farsthary.com/?p=3203As part of my continuous learning process I have decided to take several industry certifications from Adobe here in the U.S. The knowledge is the only thing that nobody can take from you

May be you find yourself in a situation where you need to install an older version of OS X, to test a software or to provide support for older versions since not everyone need to move at the speed

that OS releases cycles dictates. In Apple case that’s a problem as they don’t make it easy. Here’s some tips that could help you to do that. Shortly after a new version is released they make it impossible to just run the older installer within a more recent version.

With OS X El Capitan, Yosemite, or Mavericks, you can use a USB flash drive or other removable media as a startup disk from which to install OS X.

1-Using the Disk Utility create the partition where you will install the older version

2-Make sure you have an installer of the old version you need, either from a backup, a disk, an image, etc

3-Mount your USB flash drive or other volume. You could also use a secondary internal partition.

4-Open the Terminal app, which is in the Utilities folder of your Applications folder.

5-Use the createinstallmedia command in Terminal to create the bootable installer. For detailed usage instructions, make sure that the appropriate Install OS X app is in your Applications folder, then enter one of the following paths in Terminal:

The following examples assume that the OS X installer is in your Applications folder and the name of your USB flash drive or other volume is MyUSB:

Then restart, press the alt key during boot to select the USB source and start the installation. If you encounter this error along the process This copy of the Install OS X Yosemite application can’t be verified. It may have been corrupted or tampered with during downloading or similar usually is because the system is detecting a more recent date than the valid range for “installing” those versions, in that case you need to follow a few more steps to trick the system date into a valid one:

While at the “Install OS X” boot menu. Pull down the “Utilities” menu option and choose “Terminal” . The manual date format to use is a little weird, it looks something like mmddHHMMccyy.

In simpler terms, that is: Month Date Hour Minute Year, and it’s entered as a solid line with no breaks or spaces between the numbers. Previously go online and research the release date and the valid range of the OS you want to install and then type any date in that range. Disconnect from the internet to perform this step and type on the terminal such a date, for example for Yosemite I’ve used date 120082315 , and then you will be able to proceed with the installation, reconnect to internet and get the correct date back.

Getting there! Still remaining are some technical details but generally things are looking really interesting.

Cheers!

]]>https://farsthary.wordpress.com/2016/07/20/quadstrips-test-3/feed/0farstharyQuadStrips456Stroking improvementshttps://farsthary.wordpress.com/2016/06/02/2834/
https://farsthary.wordpress.com/2016/06/02/2834/#respondThu, 02 Jun 2016 07:10:00 +0000http://farsthary.com/?p=2834To accurately shape a stroke in QuadPaint, the user can create new pinned vertices with double click, in the future more powerful curve controls will be implemented. Today I’ve improved the implementation by allowing the deformation to be independent from stroke density. (unlike previous algorithm) and I’ve solved a bug that prevented to simultaniously deform linked strokes.

Recently I have ironed out QuadPaint and improved lots of things under the hood. So far it is shaping into an awesome and fast retopology sketch tool. Strokes also did allow to add, remove, collapse and split vertices for finer control over the output but is still not exposed to the GUI, I will add it soon. I’m considering also live previews so artists can have instant feedback over stroke changes. More importantly is the possibility to be the base of interesting new tools.

Finally I’ve made quite a breakthrough in semiautomatic retopology. What initially started as a prototype tool is evolving into a quite powerful new way to retopologize models in 3DCoat. Giving artists the freedom to experiment in an intuitive way by just drawing patches, arbitrary patches that will be optimally filled with quads.

Artist is not limited to certain number of edges , flatness or any other constraint. Just draw. I’ve also added the possibility to save and load the strokes along with the model.

The core is done, remaining now is the usability and the workflow of the tool, adding a realtime preview among other details. I’m investigating several variants and further optimizations.

I suspect this core quadrangulator algorithm will span many interesting new tools.But wait, I’m saving the real breakthrough for later

PS: Could you suggest me a good (fast, high quality) screen capture program? I’ve tried CamStudio but cannot get +30fps recording at 1080p preferably one that is HW accelerated. (using an NVIDIA GT 560M )

Dataset fitting? it must be trough the Least squares method! I keep banging in my head for few days refusing to dive into it because for anything but the trivial function

f(x) = A + Bx

it can easily overflow the brain cache and is a heavy calculation for realtime purposes… So I attempted several heuristics that failed for arbitrary datasets (user strokes in this case) and that was a non negotiable requirement for me.

So what’s the problem about? basically you have a stroke between 2 end points, actually just a set of points given because if I knew the stroke equation there would not be problem at all! And I needed to approximate that curve with a 3D Hermite spline of the form:

Problem: what magnitudes should have the tangents such as the curve best fit the original points?

Where P0 and P1 are the known endpoints. So I need to find the tangents at each of those points M0 and M1 such the resulting spline was the closest possible to that curve.
Finally I decided to get my hands dirty with pen and paper (you thougth programming happens only at a keyboard and in front of a computer? that’s typing or implementing, programming is actually thinking and it happens even when you load the brain with a complex problem and go to sleep!)

I’m posting this mainly for me, so when I find a similar problem in the future and I have flushed my current memory of this, I will remember, I don’t want to struggle again with Google and Stackoverflow to find nothing related there. (or I did a wrong search ).

How the least squares method works?

Errors between original curve and interpolated one.

You have some datasets {P0, P1 ,… Pi} you want to fit with a mathematical function F(…). That means that the sum of the approximation errors of that function should be as little as possible, ideally 0 so would be a perfect fit. And the error can be calculated as the sum of all the tiny errors for each evaluated point of the dataset squared, because we don’t want errors canceling each other on both sides of the original curve.

Easy no? well, in order to minimize that error we should take the partials derivatives of that function and set it to 0 for every unknown we want to estimate. In this case we have 2 unknown tangents.
And here’s where the heavy stuff start showing.

I needed to substitute the equations with the original forms but this brings another problem: it has 3D vectors! and the solution is not as easy as solving the least square for every component (trust me, I even attempted that!) I had to flatten it to a scalar problem.

A coordinate system transformation could have done the trick or a different parametrization:

Another parametrization perhaps?

But equations where already large and complex enough once substituted and it doesn’t account the case where in the new parametric form 2 or more values could correspond to the same parameter (remember user strokes can be like Brownian motion :P) and perhaps I can explore it once I find a more canonical solution.

And then I realized I could minimize the error LENGTH (scalar) instead of the vector difference. And went back to the beginning rewriting the least square functions:

so in order to minimize the error:

Wow, three times longer than before, take into account that each of those terms are a full equation on their own! look at this sample of my pen work

Substitutions of substitutions…

Is it correct? the reasoning was correct… so I blindly continue developing the solution, calculating the derivatives (Thanks Wolfram Alpa!) and then organize it into Matrix form (AX = B) to finally calculate the solution vector with the tangents magnitude… and crossed my fingers….

Wow, just wow, it worked flawlessly and finally integrate it into my branch of 3DCoat QuadStrips. Is mathematically heavy for realtime but it only runs once at the creation of the spline so performance here is not an issue.
The harder the problem the greater the self satisfaction I get

Cheers!

]]>https://farsthary.wordpress.com/2016/02/07/spline-fitting/feed/0farstharysplineformTangentsEstimationTangentsEstimationErrorsSumpartialderivativesTangentsEstimationTransformationsumofdistSumOfDist2partialsBighand written equiationsImproving contour partitioninghttps://farsthary.wordpress.com/2015/12/24/improving-contour-partitioning/
https://farsthary.wordpress.com/2015/12/24/improving-contour-partitioning/#respondThu, 24 Dec 2015 07:24:59 +0000http://farsthary.com/?p=2620At the heart of several tools that I have developed in the past lays a contour partitioning algorithm. It was robust and could handle arbitrary contour shapes, but recently I got a bug report assigned related to CloseHoles tool, and after a careful debugging I found that the partition was indeed robust, but not “clean” enough, it could sometimes create fan like splits which was actually undesired.
What started as a routine bug hunt ended up improving greatly the code for a much more neat contour partition algorithm.
BeforeAfter: new algorithm
]]>https://farsthary.wordpress.com/2015/12/24/improving-contour-partitioning/feed/0farstharyBeforeAfter: new algorithmQuad stripshttps://farsthary.wordpress.com/2015/11/18/quad-strips/
https://farsthary.wordpress.com/2015/11/18/quad-strips/#commentsWed, 18 Nov 2015 15:24:14 +0000http://farsthary.com/?p=2625An incredible powerful and yet conceptually simple tool are quad strips. highly requested by our community! Is on the way

Using strokes artist can easily create, place and modify full strips of quads with incredible flexibility. I’m still improving the tool flow but will have auto welding, size control and real-time or near real-time feedback as well.

Recently added cut , auto welding, automatic level of detail… important enhancement to this stroking tool. Also adjusted the tension level to make it more intuitive.

]]>https://farsthary.wordpress.com/2015/11/03/simple-stroke-test-2/feed/0farstharySimpleStroke polishhttps://farsthary.wordpress.com/2015/10/21/simplestroke-polish/
https://farsthary.wordpress.com/2015/10/21/simplestroke-polish/#respondWed, 21 Oct 2015 07:24:29 +0000http://farsthary.com/?p=2590Unlike spline based retopo strokes, this new class is oriented for more direct stroke control and manipulation: it supports splitting/reducing of divisions. Moving and smoothing etc. It is actively used in QuadPaint tool.